Today, electronic devices such as smart cards are widely used in society. For example, smart cards may be used as electronic identity (eID) cards or bank cards. Electronic devices of this kind may also be equipped with optical feedback indicators, for example light-emitting diodes. Since the electronic devices may be power-constrained, it may be desirable to control such light-emitting diodes efficiently, in particular in a power-efficient yet reliable way. This is particularly important for contactless smart cards, but also for other kinds of electronic devices, specifically for any device with an embedded microcontroller (MCU) and light-emitting diodes.